平穩加快的運行旋轉動畫

Question

我使用此代碼來旋轉任何觀點：

func rotateAnimation(theView: UIView, duration: CFTimeInterval = 20.0, repeatCount: Float = 200, toValue: CGFloat = CGFloat(.pi * 2.0)) { 
    let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation") 
    rotateAnimation.fromValue = 0.0 
    rotateAnimation.toValue = toValue 
    rotateAnimation.duration = duration 
    rotateAnimation.repeatCount = repeatCount 
    theView.layer.add(rotateAnimation, forKey: nil) 
} 

我想知道如何加快速度，目前正在運行的動畫。例如，如果一個UIView隨上面的代碼一起旋轉，那麼如何使這個速度以一個很好的轉換速度快兩倍？

因此：調用rotationAnimation：以正常速度旋轉 - >調用？函數？ - > UIView將平穩地旋轉到更快的速度 - > UIView將以所需的速度繼續旋轉。

感謝您的任何幫助。

Answer 1

請嘗試以下代碼

 let timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { (timer) in 
      self.viewToMove.layer.timeOffset = self.viewToMove.layer.convertTime(CACurrentMediaTime(), from: nil) 
      self.viewToMove.layer.beginTime = CACurrentMediaTime() 
      self.viewToMove.layer.speed += 0.5 

     } 
     timer.fire() 

它會增加動畫速度非常流暢

Answer 2

試試這個第二動畫

您可以設置較小的時間來提高速度

func rotateAnimation(theView: UIView, duration: CFTimeInterval = 0.4, repeatCount: Float = 200, toValue: CGFloat = CGFloat(.pi * 2.0)) { 
    let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation") 
    rotateAnimation.fromValue = 0.0 
    rotateAnimation.toValue = toValue 
    rotateAnimation.duration = duration 
    rotateAnimation.repeatCount = repeatCount 

並設置shouldRasterize =真有更好的表現

theView.layer.rasterizationScale = UIScreen.main.scale 
    theView.layer.shouldRasterize = true 

使用兩個相同的密鑰動畫

theView.layer.add(rotateAnimation, forKey: "animation") 
} 

Answer 3

將repeatcount設置爲1，並在每個動畫停止後重新添加動畫。我不確定這是否會導致性能問題，因爲我使用非常基本的方形視圖進行測試。

通過添加CAMediaTimingFunction參數，你可以控制是否使用kCAMediaTimingFunctionLinear - 爲那些正常的動畫循環，或者使用一個自定義，如kCAMediaTimingFunctionEaseIn - 爲關鍵幀動畫顯示的平滑過渡。

// your function to start the acceleration 
@IBAction func buttonTapped(_ sender: UIButton) { 
    accel = true 
    speed = 2.0 
    timeOffset = self.rect.layer.convertTime(CACurrentMediaTime(), from: nil) 
    timeOffset = timeOffset - lastStart 
    // memorize the timeoffset, new speed (2x) and a boolean flag 
    self.rect.layer.removeAllAnimations() 
} 

// delegate - memorize the CFTimeInterval 
func animationDidStart(_ anim: CAAnimation) { 
    lastStart = self.rect.layer.convertTime(CACurrentMediaTime(), from: nil) 
} 

// delegate - start a new loop of animation each time it's stopped 
func animationDidStop(_ anim: CAAnimation, finished flag: Bool) { 
    if accel { 
     accel = false 
     let opt = CAMediaTimingFunction(controlPoints: 0.5, 0.2, 0.9, 0.7) 
     rotateAnimation(theView: rect, speed: speed, fromValue: CGFloat(.pi * 2.0 * Float(timeOffset)/10.0), toValue: CGFloat(.pi * 2.0 * Float(timeOffset)/10.0 + .pi * 2.0), option: opt) 
    } else { 
     rotateAnimation(theView: rect, speed: speed, fromValue: CGFloat(.pi * 2.0 * Float(timeOffset)/10.0), toValue: CGFloat(.pi * 2.0 * Float(timeOffset)/10.0 + .pi * 2.0)) 
     // note that timeOffset is initialize to be 0. 
    } 
} 

你想在這裏自定義CAMediaTimingFunction，通過0.5的斜率開始，逐漸增加至1.0，我這裏沒有優化的貝塞爾曲線，你可以做自己想要的曲線。

最後一個小調整到您的動畫功能：

func rotateAnimation(theView: UIView, speed: Float, duration: CFTimeInterval = 10.0, fromValue: CGFloat = CGFloat(0.0), toValue: CGFloat = CGFloat(.pi * 2.0), option: CAMediaTimingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)) { 
    let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation") 
    rotateAnimation.fromValue = fromValue 
    rotateAnimation.toValue = toValue 
    rotateAnimation.duration = duration 
    rotateAnimation.speed = speed 
    rotateAnimation.repeatCount = 1 
    rotateAnimation.delegate = self 
    rotateAnimation.timingFunction = option 
    theView.layer.add(rotateAnimation, forKey: nil) 
}